Surge-compensated liquid pump



Oct. 25, 1949. A. T. LAsPE: ET AL 2,435,752

SURGE-COMPENSATED LIQUID PUMP Filed Feb. 19, 1947 V 2 Shets-Sheet 1 F1G. I. 2 FIGS.

IOI

Patented Oct. 25, 1949 UNITED STATES PATENT OFFIQE SURGE-COMPENSATED LIQUID PUMP Missouri Application February 19, 1947, Serial No. 729,602

4 Claims.

This invention relates to liquid pumps, and with regard to certain more specific features, to surge compensated lubricant-dispensing pumps.

Among the several objects of the invention may be noted the provision of a lubricant-dispensing pump which, although operated by a direct-connected reciprocating air engine tending to produce surging, land will in fact produce a substantially uniform discharge flow; the provision of a pump of the class described wherewith surging efiects are minimized to the point that they do not deleteriously affect lubricant delivery; the provision of a pump of the class described in which surge compensation is by means of a convenient and compact structure automatically maintained at optimum efficiency; and the provision of a pump of this class which is simple in form and reliable in operation. Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingl comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structure hereinafter described, and the scope of the application of which will be indicated in the following claims.

In the accompanying drawings, in which one of Various possible embodiments of the invention is illustrated,

Fig. 1 is a side elevation of a lance type of lubricating pump embodying the invention;

Fig. 2 is an enlarged fragmentary vertical section taken on line 2--2 of Fig. 1;

Fig. 3 is a fragmentary left-hand elevation of Fig. 2 and including a broken-away section taken on line 33 of said Fig. 2;

Fig. 4 is a fragmentary detail section taken on line 4-4 of Fig. 1, and constituting a downward continuation of Fig. 2; and,

Fig. 5 is an enlarged vertical section taken through a pressure-compensating elesnen t.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

The general class of pumps to which the present invention applies is referred to in U. S. Patents 2,215,852 and 2,269,423. Generally speaking, such a pump consists of a so-called lance type of lubricant pump cylinder adapted to be inserted into a barrel or the like of lubricant for pumping lubricant therefrom. This pump is surmounted by an integral reciprocating air engine which operates the pump. The air engine and the lance form a unit, the lance of which may be insented through an opening in the top of a drum while the air engine is supported at the upper end of the lance outside of the drum. The inlet of the pump constituting the lance is within the drum and the outlet is outside of and above it. This outlet ordinarily has connected with it a flexible lubricant line on the end of which is a valve-controlled delivery nozzle for delivering lubricant to the required points. In View of the fact that apparatus of this general nature is referred to in said patents, onl such details thereof as are required for describing the present invention will be particularized herein.

One of the characteristics of apparatus of the class described above is that the lubricant pump is essentiall of the single-stroke variety. That is to say, on one of its strokes (the up stroke), it has its largest volumetric displacement. Upon the down stroke the Volumetric displacement is small or nil. Another way of stating this is that the lubricant pump is essentially a lift pump. This accounts for a definite surging action which is undesirable at the outlet nozzle. This surging is intensified by reason of the fact that the frictional resistance against a large volumetric flow is greater than that against a smaller or nil volumetric flow and hence the required air pressure on the up stroke of the air engine is greater than that used upon the down stroke. The present invention by very simple means overcomes the stated surging in apparatus of the class described or its equivalent.

Referring now more particularly to the drawings, there is shown at numeral -I a lance-type of lubricant pump having a pump cylinder 3. Cylinder 3 has a lower inlet opening 5 adapted to receive lubricant when the bottom of the cylinder is inserted into the lubricant of the drum, which is usually at or near the bottom. Adjacent the opening 5 is a foot or check valve 7 which opens inward in response to flow into the cylinder 3 from the opening 5, but checks shut against any tendency of lubricant to flow from the cylinder 3 out through the inlet 5. Sliding in the cylinder 3 above the check valve 7 is a piston indicated generally by the numeral 9. This piston is carried on the lower end of a piston rod H. The piston 9 is constituted by a head l3 upon which seats an open member l5, the latter being slidable on the lower end of the rod H and biased to a seat on l3 by means of a spring I! reacting from an anchor [9 on shaft l I. The member l5 slides in the cylinder 3 and has packing rings 2| engaging the cylinder. It has openings 23 which, when the member I5 is unseated, permit flow from below the piston to points above it.

In View of the above it will be clear that when the piston 9 is reciprocated in the piston I a pumping action will occur. Upon a down stroke, lubricant in the cylinder I which is trapped above the check valve I will force the member I5 from its seat on I3 thus progressing to a position above the descending piston and becoming located in the parts of the cylinder I above said piston. Upon an up stroke, the lubricant above the then closed piston is forced out toward the upper end.

of the cylinder I while an additional charge is drawn in below the piston through the check valve I. In order to eliminate descriptionv not germane to the invention, the usual air eliminator used in connection with pistons such as 9 has not been shown.

At the upper end of the. cylinder I is a. bung bushing by means of which the apparatus is attached to the upper head of the lubricant drum. The drum is not shown, being a standard article of commerce. In the bung bushing 25 is the pump outlet 2?.

The air engine 29 for operating the lubricant pump described surmounts said pump, the upper end 3| of the bung bushing 25 forming the lower head of this air engine, The upper hollow head of the engine is shown at numeral 33-. Between the heads 31 and 33 is the air engine cylinder 35 held in place by means of draw studs 38 connestin said heads.

In. the cylinder 35 is a piston 31 carried on a hollow piston rod 39. which. extends through. packings 4| in the lower head 3I and is connected through a hollow coupler 53 to the pump rod II. The hollow coupler 43 includes a. cylindric space 45 in which is carried a head 51 at the lower end of the valve stem 49. This hollow coupler 4.5 allows for lost motion between the reciprocating action of the piston SI and the desired reciprocating action of the valve stem 49. When the piston 31 reciprocates in the cylinder 35 it directly reciprocates the rod I I of the pump, but reciprocation of the valve stem 59 is only accomplished with lost motion so that the stem is reset to one of its positions or another at the endsoi the strokes of the piston 3I.

Within the, hollow head 33 is a snap-acting, over-centering valve mechanism 5I which is operated by the valve stem 49 to re-set. a sliding D-valve 53 for controlling flow of compressed air from the inside of the valve chamber 5I to ports 57 and 59 respectively. The D'-valve 53 when uncovering one port 59 admits air to it and at the same time places the other port 51 in communication with an exhaust port 55. Conversely, when the port 59 is covered and the port 51 exposed, compressed air will flow into the latter andv exhaust will occur from the former. The D-valve 53 is operated with lost motion from a shoe SI. The shoe 6i in turn is operated with lost motion from a sleeve 63 attached to the valve stem 49. Further description of the details of the operating mechanism between the valve stem 49 and the D-valve 53 will not be given since it is described in detail in said Patent 2,269,423. It sufiices to say that the D-val-Ve 53 is re-set' each time that the piston 31- approaches the end of its, stroke. In Fig. 2 it is shown in its upper position.

At numeral 55 is shown an inlet coupler for receiving an air hose (not shown) for supplying compressed air to the valve chamber 51 from a suitable compressed air supply tank,

The: valve port 59 is in communication with the upper end, of the cylinder 35 through a passage 61. The port 51 is in communication with the lower end of the cylinder 35 through passages 69, II and I3. Assuming that in Figs. 2 and 3 air is supplied under pressure to the fitting 55 of the valve chamber formed by the hollow head 33, flow occurs through the passage 61 to the upper side of the piston 31, thus driving it down. At this time air which was under the piston 3! from the previous stroke is exhausted through ports I3, II, 69, 51, through the D-valve 53 and to the exhaust port 55. Under these conditions lubricant is transferred from the under side to the upper side of the pump piston 9 and very little is driven out through the pump outlet port 21. The small amount of lubricant that may be driven out due to the intrusion into the pump cylinder 3, of the pump rod I I is negligible for the present purposes. When the piston 31 arrives at a point near the bottom of its stroke, the valve mechanism 5I trips the D-valve 53 to its alternate position connecting port 59 with the exhaust 55 and exposing port 5I to inlet pressure. This admits air under pressure to passages 5I, 69, "II and I3 to. the bottom side of the piston 31', thus. raisin it while air above the piston exhausts through passages 67, 59 and 55, passing under the D-Valve 53. elevates the pump piston 9, thus compressing the lubricant charge above it and forcing the. charge through the pump outlet H and into the line I5. If the. valve at the end of line I5 is shut, then the air engine and pump will stall when he total. pump piston pressure becomes enough to equal. the total air pressure on the piston 37. However, when ever said valve is open, the air engine will continue to operate the pump to discharge lubricant, because then the resistance to pump discharge fluid is lower than the applied pressure from the air engine. The air pressure required for the purpose is, however, substantial because of line friction.

In view of the above it will be seen that the air pressure required underneath the piston 5! for a pumping or lift stroke is greater than the air pressure required above it for the down-- ward returnv stroke of the pump piston 9. This fact is taken advantage of in carrying out the objects of thev invention. To this end a ported connection is made at T1 with the air inlet passage 51 which leads to the top of the piston. 37. This connection II communicates with a short line I9 leading to the upper end.- of a compensat'- ing device. 8|. This device 8| is quite close to the engine cylinder 35. Its construction is detailed in. Fig. 5 wherein. it will be seen to consist in an upper head 83 and a lower head; 85 on a cylinder 81. In the lower. head is a cross connection. 89 between. the pump outlet 21 and the line I15. Above the connection 85 is a rig-id reticulated guard plate 9|? which admits lubricant under lubricant line pressure into. the. cylinder 81. This pressure is applied to the outside of a resilient bladder 93 composed of synthetic rubber or the like and carrying air in its interior 9-5. This bladder is of more orless cylindric form as shown and includes side rib-like indentations, one of which is shown in Fig. 5 and numbered 91. Such ribs inhibit longitudinal collapse of thev bladder while permitting lateral compressibility. The bladder is supported between the cylinder ill and the head 83 by means of a clamped flange 99. The short line 19 communicates; with the interior of the bladder through a connection IIlI which is a check valve I03 such as used on The rising piston automobil tire inlets. This allows inward flow of air but checks outward flow.

Beneath the opening I05 which admits air from the head 83 into the bladder 93 is a rigid angled plate I01 attached to the head 83. This plate is not in the nature of a check valve but merely acts as a guard over the port I95 to prevent any adjacent portions of the bladder 93 from being jammed into the port I05 under possible extreme conditions of collapse.

The purpose of the screen 9! is to prevent the bladder 93 from expanding into the connection 89 under any possible extreme conditions of expansion.

Operation is as follows, assuming that an air line connection is made with the fitting 65 so as to deliver air to the chamber 33. The pressure is at ordinary line pressure such as will be found at most garages, say of the order of 150 to 200 p. s. i. It is also assumed that the valve at the end of line 15 is open. Starting with conditions such as shown in Fig. 2, the air will enter the port 69 and pass through the passage 61 to the top of piston 31. The piston will be driven down thus to drive down the pump piston 9 for transfer of lubricant from the bottom side to the top side of the piston. Since the pressure required to move the piston 31 under these conditions is not the full 150 to 200 p. s. i. and since the valve port 59 is relatively small, there will be a throttling action of the air through that port 59 so that the pressure in the passage 61 and above the piston 31 does not reach full line pressure. For example, it will become 90 p. s. i. This reduced pressure is communicated through port 11, line 19 and check valve I93 to the interior 95 of the bladder 93 thus tending to expand the bladder. After the piston 31 has descended, the D-valve 53 becomes tripped to cut communication of air from the valve chamber 33 to the top of the piston, and establish communication through port 51 and passages 69, 1| and 13 with the lower side of the piston 31, thus driving the piston upward. This discharges the lubricant on the upper side of the pump piston 59 out through the port 21, passage 89 and outlet pipe 15. As above stated the friction in the outlet line 15 requires a higher operating air pressure than the above stated 90 p. s. 1. Thus, although the port 51 is also a restricted port, the piston does not move until time has allowed pressure to be built up sufficiently for the purpose. This pressure will be much closer to the line pressure of 150 to 2-00 p. s. i. At this time the previously applied 90 p. s. i. pressure in the bladder 93 is trapped therein b the check valve I93. Thus the larger pressure in the communicating passage 89 will constrict the bladder 93 against its lower interior pressure.

It will be seen that upon the next downstroke of the piston 31 there would ordinarily be no more sustaining pressure in the line 15. The resulting variations in pressure in the line 15 are the cause of the stated surging or spurting action for which it is designed to compensate. The compensation is provided by the fact that when the piston 31 is descending, the resilient air pressure in the bladder 93 will tend to re-expand it and thus supply pressure for continued flow in the line 15. While the lubricant flow supplied under the expansive action of the bladder 93 (during downward movement of the piston 31) is not under the higher pressure supplied by the upward movement of the piston 31, it is nevertheless under the substantial pressure of p. s. i. or so. Thus is avoided the surging or spurting which normally would be caused by intermittent almost complete loss of pressure. Thus compensation is effected dLu'ing the low pressure part of the cycle of the lubricant pump I and a relatively smooth non-spurting and nonsurging flow is obtained in the pipe 15.

The purpose of the check valve I03 is to maintain the pressure in the bladder 93 during periods when the passages 61 and 11 are at exhaust pressure. It will be noted in this connection that upon every cycle of the apparatus a pressure impulse is applied to the valve I03. If perchance during idle periods leakage of pressure should have occurred from the bladder 93, it will upon starting be made up by the reception of air from passages 61 and 11. Thus an operator is assured that whenever his pump is coupled to the air supply line at the coupler 65 his compensator will become charged and will automatically remain charged.

A feature of the invention particularly to be noted is that the bladder connection is made to the low-pressure connecting port 61, as distinguished from the high-pressure connecting port 69. Consequently, the bladder is of a more resilient nature than it would otherwise be; or. stated otherwise, its coefiicient of volumetric change is higher. Hence the compensator cylinder 8! will receive a larger volume of lubricant upon a pressure stroke of the pump I so as to have this larger volume available for a longer period of compensated flow between surges, thus more effectively smoothing out the flow. If the bladder 93 is pumped up too hard, as by direct application of air line pressure, then the effective compensation becomes too small.

It will be not-ed that the invention avoids the ineffectiveness of merely directly charging a compensating bladder from a point ahead of D-valve 53, that is, from the main air line or the equivalent.

It will be observed from the above description that the invention is operative in principle for a substantial range of line pressures found at most garages. However, the pressure reduction in passages 61 and 11, due to throttling action through the valve port 59, may be different for different line pressures and also for different designs of port 59 and passages 61 and 11. With the apparatus shown, for optimum or near optimum results, the reduced pressure in passages 61 and 11 is of the order of 90 p. s. i. or so, for a line pressure of to 200 p. s. i., as above described. In the cases of other port designs, for optimum results, other line pressures may be desirable in order to obtain the most desirable relative pressure conditions in passage ports 61 and 11. To obtain such other line pressures, if the normal air-line pressure is too high, an ordinary pressure-reducing regulator (not shown) may be used to control the line pressure which enters the fitting 65.

It is to be understood herein that the invention is applicable to all liquid pumps with direct-connected reciprocating air engines which are essentially of the single-acting variety. The term single-acting as applied to the liquid pump is not to be construed as limited to pumps wherein all of the pumping action is on one stroke; but it is intended to apply to pumps wherein a preponderating part of the pumping action is on one stroke. It is this preponderance of pumping action that accounts for the different pressures carried in the air passages leading from the valve of the direct-connected engine, and advantage is taken of this by connecting the expansive compensator with the air passage in which the lower air pressure occurs.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As. many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. Asurge compensator for-a reciprocating liquid pump having a, direct-connected reciprocating-piston air engine, the pump having an outlet liquid passage and the air engine having an automatic valve control for its air supply and having air passages leading from the valve control to opposite sides of the piston; comprising means providing a space communicating with the pump outlet, a resilient member in said space exposed on-one side to liquid. pressure in the space and on the other side to air pressure, and means for commun-icating air pressure to the air-side of the resil-ient member from one of said air engine passages.

2. A surge compensator for a reciprocating liquid pump requiring more pressure on one stroke than the other and having'a direct-connected reciprocating-piston air engine, the pump having an outlet liquid passage and'the air engine having an automatic valve control for its air supply and having air passages respectively carrying different air pressures and respectively leading from the valve control to opposite sides of the piston; comprising means providing a substantial space communicating with'the pump outlet, a resilient and substantially expansible member in said space exposed on one side to liquid pressure in the space and on the other side to air pressure, and means for communicating air pressure to the air-side of the resilient member from the one of said air engine passages which carries the lowest air pressure.

3. A surge compensator for an essentially single-acting reciprocating liquid pump having a direct-connected reciprocating-piston air engine, the pump having an outlet liquid passage :and the air engine having an automatic valve control for its air supply and having air passages respectively carrying diiTerent air pressures and respectively leading from the valve control to opposite sides of the piston; comprising means providing a substantial space communicating with the pump outlet, a substantially resilient bladder member in said space exposed on one side to liquid pressure in the space and on the other side to air pressure, and means for communicating air pressure to the air-side of the resilient bladder member from the one of said air engine passages which carries the lowest air pressure.

4. A surge compensator for a reciprocating liquid pump requiring more pressure on one stroke than the other and having a direct-connected reciprocating-piston air engine, the pump having an outlet liquid passage and the air engine having an automatic valve control for its air supply and having air passages respectively carrying different air pressures and respectively leadingfrom the valve control to opposite sides of the piston; comprising means providing a substantial space communicating with the pump outlet, a substantially resilient member in said space exposed on one side to liquid pressure in the-space and on the other side to air pressure, means for communicating air pressure to the air-side of the resilient member from the one of said air engine passages which carries the lowest air pressure, and a check valve in said communicating means for freely admitting air under the last-named air pressure to said resilient member but preventing escape of said air in the absence of said last pressure.

ALBERT T. LASPE. JOHN R. GRAEF.

REFERENCES CITED The following'references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,269,423 Barke et a1. Jan. 13, 1942 2,324,701 Herman July 20, 1943' 2,347,379 Teeter Apr. 25, 1944 

